Enormous flying reptiles of Berengaria VII, reported to breathe fire and to exceed two hundred metres in length, which Spock once claimed to have seen for himself.
The dragons of Berengaria VII are huge flying reptiles and the nearest thing in known space to the monsters of Earth legend.
In This Side of Paradise, Spock, under the influence of the spores of Omicron Ceti III, lies in the grass with Leila Kalomi watching the clouds. When she says one looks like a dragon, he replies that he has seen a real dragon on Berengaria VII, and that he had never before stopped to look at clouds.
The planet is visited a century earlier in the Enterprise episode Bound, when Archer's crew survey it as the site of the first Starfleet starbase. Archer notes that it has fire-breathing flying reptiles more than two hundred metres long.